Research in this laboratory focuses primarily on the role of lymphocytes and macrophages in the regulation of connective tissue metabolism associated with inflammatory reactions. Antigen specific activation of lymphocytes results in the production of biologically active lymphokines. One of these lymphokines has the ability to stimulate fibroblasts to divide and to increase their synthesis of both collagen and noncollagen protein. Another lymphokine, macrophage activation factor, activates macrophages. Macrophages also produce a molecule which enhances fibroblast function. Activation of macrophages by MAF and other stimulants involves prostaglandin generation and alterations in intracellular levels of cAMP. By these mechanisms the immune system may modulate connective tissue metabolism in inflammatory lesions.